Hitherto, according to a bending apparatus such as a press brake, a line to be bent is successively selected based on product information to determine a bending sequence (manually or automatically), tools including a punch attached to an upper table and/or a die attached to a lower table, and a tool (processing station) at each bending sequence. The predetermined tools are put at predetermined positions on upper and lower tables based on the determined tool layout, then the foot switch is turned on to start up a ram on the upper or lower table, and a workpiece is bent.
In a bending apparatus like that, recently, such a step bending has become mainstream that multiple processing stations are provided and a worker moves to a predetermined processing station at each bending sequence so that multiple processing steps can be performed as products have been complicated.
With respect to the step bending, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-295057 and No. 2000-351018, a foot switch is moveable to a point in front of a predetermined processing station at each bending sequence, or to a point in front of a center point C of back-ends of a workpiece against which abutments are abutted (FIG. 3 in Japanese Patent Application Laid-Open No. 9-295057), whereby the burden of workers is reduced.
In the step bending process, however, there are cases where bending lines on the workpiece, which is an object to be processed, are present on an end part in the left-right direction of the workpiece. In such a case, even if the foot switch can be moved in front of the processing station or in front of the center point of the back-ends of the workpiece, as mentioned above, a distance between an actual processing point (an end part in the left-right direction of the workpiece) and the foot switch is long.
As a result, workers have to have an improper posture and it is very difficult to work, and accordingly the work efficiency is apparently lowered. Further, a workpiece abutting accuracy expressing a degree of contact properness between the workpiece and the abutment is lowered, and accurate flange sizes cannot be obtained.
On the other hand, according to the conventional technique, when after one step (a bending) is finished, a foot switch starts moving toward a target, a next processing station. At that time a worker sometimes keeps his/her foot on the foot switch, and also, such a case may happen that a body part of the worker enters the region of movement while the foot switch is moving.
As a result, the worker faces a very big danger, the safety is not ensured, and a big accident sometimes occurs.
The object of the present invention is to provide a bending apparatus capable of improving the work efficiency by providing a moveable foot switch to a point in front of an actual bending point as well as ensuring the safety of workers by preventing the foot switch from moving when a foreign object including a body part of the worker is present in a region of movement of the foot switch, or by detecting the entry of the foreign object and emergently stopping the foot switch when the foreign object enters the region of movement even after the foot switch has once started moving.